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Page Content. Spanish Hmong Somali. Forensic Testing Services. Drug Chemistry. Questioned Documents. Latent Prints. Careers in Forensic Science. Breath Testing Program. Courtroom Testimony. The bottom half of the bag is then taped to the door, leaving the top half open to allow access to the bag. Placing one-inch slits around the zippered mouth of the bag creates flaps that can be taped to the door.
Before the fuming begins, a test print must be placed inside the freezer bag to serve as a control. This allows the progress of the fuming process to be gauged to indicate when the procedure is finished. Using an ungloved finger, wipe an oily area of your face, such as your forehead or along the sides of your nose. Next, reach that finger inside the freezer bag and place a fingerprint four to five inches inside the opening, on the bag.
On the exterior of the bag, use a marker or pen to draw a circle around the area where you left the test print. This will serve as a reference to help you find your test print. Next, place five to six drops of superglue on the surface of one of the prepared cotton balls. Working quickly, carefully add the cotton ball to the freezer bag through the unsecured top. Be certain to prevent the ball from coming into contact with the doorknob, and be careful not to drip any superglue on the doorknob.
Finally, tape the top of the bag to the door to create an airtight fuming chamber around the doorknob see Figure 2. Figure 2: Plastic bag is taped over the doorknob to provide a fuming chamber. Note the presence of a test print. Note also that flaps have been cut around the mouth of the bag to aid in the taping procedure.
The reaction between the superglue and cotton ball, expedited by the dried baking soda, begins producing fumes almost immediately. Although the fumes themselves may not be visible, the effects they have on any latent prints will be obvious within several minutes.
Depending upon various factors, such as ambient temperature, the time necessary for the fuming process can range from five to 15 minutes.
Allowing the doorknob to fume for too long will result in the ridge detail and minutia of the print becoming obscured. Therefore, it is crucial to monitor the test print and begin venting the bag once the test print shows signs of whitening.
Vent the bag by removing the tape from the top and allowing the fumes to dissipate for several minutes. Be certain not to place your face near the bag while venting, as the fumes will cause eye and lung irritation.
After the majority of the fumes have dispersed, the bag can carefully be removed and discarded. Print Enhancement. Now that any fingerprints are visible and fixed by the superglue-fuming process see Figure 3 , there are several options available for enhancement and collection. Individual preferences, the severity of the crime being investigated, and the availability of equipment are all factors in determining the best method to utilize.
If the nature of the crime warrants, the preferred method is to remove the doorknob and submit it to the lab after fuming. Although any prints should be relatively secure, excessive handling or rubbing should be avoided. With the actual doorknob in hand, the lab can use an assortment of different dye-stains, such as MRM, that react with the superglue to fluoresce under an alternate light source see Figure 4.
Figure 4: Fumed print with MRM dye stain illuminated by an alternate light source nanometers under lab conditions. If attempts are to be made at lifting the fingerprint in the field, photography should always occur first. Macro, medium range, and overall photographs—both with and without a reference scale—should all be taken, with emphasis on the macro.
Once the photography is complete, the prints may be enhanced with black volcanic fingerprint powder. Clear lifting tape can then be used to lift and transfer the print to a clear acetate sheet or other backing material see Figure 5.
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